Store ejection systems are commonly used on military aircraft to carry and release stores such as bombs, missiles and other weapons and materials. Such store ejection systems are typically mounted on an underside of the aircraft such as on a wing pylon or in a fuselage bay. Stores are supported from the store ejection system by a pair of suspension hooks.
In order to avoid the risk of collision with the aircraft, the store is typically forcibly ejected away from the airflow surrounding the aircraft after the store is released from the suspension hooks. The store ejection system may include a pair of forward and aft ejector pistons that push the store casing downwardly and away from the aircraft. Compressed fluid such as pressurized gas (e.g., compressed air) is commonly used as the medium for forcing the ejector pistons outwardly to eject the store clear of the aircraft.
In addition to ejecting the store away from the airflow surrounding the aircraft, it is also necessary to eject the store in a controlled manner to avoid problems associated with improper store separation. In the case where the store is a weapon, such problems can result in failure of the weapon to deploy. Improper store separation can also result in tumbling of the store which may compromise the functionality of guidance systems contained within the store and which serve to guide the store to a target. For example, some stores such as missiles carry gyroscopic guidance systems that stabilize the missile during flight and assist in the accurate delivery of the missile toward its target. An ejection of the store that results in a tumbling of the missile may result in the loss of the missile. In extreme cases, improper store separation may result in the store striking the aircraft which can result in loss of aircraft and crew.
In recognition of the need to eject the store away from the aircraft in a controlled manner, some store ejection systems include a means for controlling the pitch of the store upon release. Attempts to control the pitch of the store include varying the amount of ejection force at the forward and aft ejector pistons. For example, in order to produce a nose down pitch of the store, the amount of force produced by the forward ejector piston may be increased accompanied by a decrease in the amount of force produced by the aft ejector piston. The disparity in force required at the forward versus aft ejector pistons has in the past been facilitated through the use of metering devices that apportion the amount of pressurized gas flowing to each of the ejector piston.
Unfortunately, such metering arrangements are only adjustable on the ground prior to flight and must be set according to the flight condition (e.g., speed, altitude, pitch, acceleration) of the aircraft that is predicted to occur during release of the store. Once airborne, if the actual flight condition at time of store release differs from the predicted flight condition, the store may eject with an improper pitch attitude. As mentioned above, such improper pitch attitude of the store may result in failure of the store (e.g., weapon) to deploy correctly result in loss of the weapon and/or loss of the aircraft should the weapon strike the aircraft.
In light of the increasingly higher speed capabilities of the newer generation of military aircraft, the need for accurate pitch control during store release is more pronounced. Many of these newer aircraft must deliver stores over an increasingly wide range of flight regimes which may include operation of the aircraft in the supersonic range. Due to the increasing variety of flight conditions over which the aircraft operate, it is necessary to impart an accurate pitch attitude to stores that are released such that the stores may safely penetrate the airflow surrounding the aircraft in a controlled manner.
As can be seen, there exists a need in the art for a system and method for adjusting the pitch attitude that is imparted to an ejected store such that the pitch attitude corresponds to the flight condition of the aircraft at time of store release. In addition, there exists a need in the art for a system and method for adjusting the store pitch attitude for a wide range of flight conditions of the aircraft at time of store release. Finally, there exists a need in the art for a system and method for adjusting the pitch attitude that is imparted to an ejected store and which allows for a high degree of accuracy and adjustability.